devices: remove user_command from proxy device

The only device that used user_command was Serial. This change makes
Serial device use a thread to read from its input instead of using
user_command.

BUG=chromium:1033787
TEST=./build_test
     run crosvm with stdio serial with and without sandbox

Change-Id: Ia0f2ee83d94ad2fee3f1f4f89aa734b976e33507
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1966435
Tested-by: Zach Reizner <zachr@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Dylan Reid <dgreid@chromium.org>
Commit-Queue: Zach Reizner <zachr@chromium.org>
Auto-Submit: Zach Reizner <zachr@chromium.org>

1 files changed, 2 insertions, 38 deletions

diff --git a/devices/src/proxy.rs b/devices/src/proxy.rs
index 927ea7a..cb7ebd6 100644
--- a/devices/src/proxy.rs
+++ b/devices/src/proxy.rs
@@ -56,7 +56,6 @@ enum Command {
         data: [u8; 4],
     },
     Shutdown,
-    RunUserCommand,
 }
 
 #[derive(MsgOnSocket)]
@@ -66,11 +65,7 @@ enum CommandResult {
     ReadConfigResult(u32),
 }
 
-fn child_proc<D: BusDevice, F: FnMut(&mut D)>(
-    sock: UnixSeqpacket,
-    device: &mut D,
-    mut user_command: F,
-) {
+fn child_proc<D: BusDevice>(sock: UnixSeqpacket, device: &mut D) {
     let mut running = true;
     let sock = MsgSocket::<CommandResult, Command>::new(sock);
 
@@ -114,10 +109,6 @@ fn child_proc<D: BusDevice, F: FnMut(&mut D)>(
                 running = false;
                 sock.send(&CommandResult::Ok)
             }
-            Command::RunUserCommand => {
-                user_command(device);
-                sock.send(&CommandResult::Ok)
-            }
         };
         if let Err(e) = res {
             error!("child device process failed send: {}", e);
@@ -146,31 +137,9 @@ impl ProxyDevice {
     /// * `jail` - The jail to use for isolating the given device.
     /// * `keep_fds` - File descriptors that will be kept open in the child.
     pub fn new<D: BusDevice>(
-        device: D,
-        jail: &Minijail,
-        keep_fds: Vec<RawFd>,
-    ) -> Result<ProxyDevice> {
-        Self::new_with_user_command(device, jail, keep_fds, |_| {})
-    }
-
-    /// Similar to `ProxyDevice::new`, but adds an additional custom command to be run in the forked
-    /// process when `run_user_command` is called.
-    ///
-    /// Note that the custom command closure is run in the main thread of the child process, which
-    /// also services `BusDevice` requests. Therefore, do not run blocking calls in the closure
-    /// without a timeout, or you will block any VCPU which touches this device, and every other
-    /// thread which needs to lock this device's mutex.
-    ///
-    /// # Arguments
-    /// * `device` - The device to isolate to another process.
-    /// * `jail` - The jail to use for isolating the given device.
-    /// * `keep_fds` - File descriptors that will be kept open in the child.
-    /// * `user_command` - Closure to be run in the forked process.
-    pub fn new_with_user_command<D: BusDevice, F: FnMut(&mut D)>(
         mut device: D,
         jail: &Minijail,
         mut keep_fds: Vec<RawFd>,
-        user_command: F,
     ) -> Result<ProxyDevice> {
         let debug_label = device.debug_label();
         let (child_sock, parent_sock) = UnixSeqpacket::pair().map_err(Error::Io)?;
@@ -181,7 +150,7 @@ impl ProxyDevice {
             match jail.fork(Some(&keep_fds)).map_err(Error::ForkingJail)? {
                 0 => {
                     device.on_sandboxed();
-                    child_proc(child_sock, &mut device, user_command);
+                    child_proc(child_sock, &mut device);
 
                     // We're explicitly not using std::process::exit here to avoid the cleanup of
                     // stdout/stderr globals. This can cause cascading panics and SIGILL if a worker
@@ -214,11 +183,6 @@ impl ProxyDevice {
         self.pid
     }
 
-    /// Runs the callback given in `new_with_custom_command` in the child device process.
-    pub fn run_user_command(&self) {
-        self.sync_send(&Command::RunUserCommand);
-    }
-
     /// Send a command that does not expect a response from the child device process.
     fn send_no_result(&self, cmd: &Command) {
         let res = self.sock.send(cmd);